Increasing the humidity of the air in building is especially desirable in the wintertime. Such humidification is typically accomplished through the use of an air-treating apparatus generally known as a humidifier. In general, a humidifier increases the moisture content of the air by providing a moistened evaporator pad through which air is forced. The air flow causes water from the evaporator pad to evaporate thus increasing the moisture content of the air.
For purposes of convenience, the air-treating apparatus of the present invention will often be referred to as a humidifier. However, it will be appreciated that the air-treating apparatus of the present invention may have other primary abilities, such as air temperature control, and may have different configurations than that described herein. Therefore, the present invention should not necessarily be limited to those apparatus known commercially as humidifiers, it being understood that the present invention may have applicability and utility in other industries and to other apparatus capable of performing the functions described herein.
Generally, an air-treating apparatus includes a housing and some sort of evaporator means mounted therein. Evaporator pads are typically used in humidifiers and are specifically discussed herein, but it will be appreciated that other means such as wood slats, as typically used in cooling towers, and other types of evaporator articles have also been employed in various air-treating apparatus and may be suitable for the present invention.
An evaporator pad typically comprises multiple layers of water absorbent material which form a mesh-like structure that may be continuously wetted, typically from above. Aluminum mesh is one common material from which the evaporator pad may be typically fabricated. The proper distribution of water onto the evaporator pad is an important consideration in the design of a humidifier. Desirably, the water should be uniformly distributed over the entire evaporator pad. When water is unevenly distributed, the humidifier is less efficient since one part of the evaporator pad may not be used while another part may be oversaturated, causing water run-off.
Providing uniform distribution is particularly difficult because humidifiers are often unevenly mounted when installed. Such errors in installation typically result in the apparatus being tilted slightly to one side when it is mounted. Even when an apparatus is mounted in accordance with the mounting instructions, the apparatus may still not be perfectly level because the duct or plenum on which it is mounted may be tilted to some degree. In either case, the efficiency of the humidifier is typically reduced because water is unevenly distributed onto the evaporator pad.
One solution to the problem of unequal distribution of water due to tilted installation is to provide a source of water for each delivery point above the evaporator pad. It will readily be appreciated that this "multiple source" arrangement, while functional, is much more costly in terms of both the number of additional parts required and the amount of water used. Thus, the solution is not seen in the industry as being a practical alternative.
Another solution to this problem is to provide extremely deep channels in a distribution tray located above the evaporator pad that will fill with water and overcome the angle of tilt. Although potentially functional, this method is also very inefficient and costly. Clearly, in order to overcome the angle of tilt, significant amounts of water will be necessary and even then, the amount of water received by one side of the evaporator pad might not be equal to the amount of water received at the other side, unless there is a sufficient rate of water flow to cause the desired result. The design of a high-walled distribution tray also tends to undesirably enlarge the overall dimensions of the humidifier.
U.S. Pat. No. 3,193,259 to Liebmann discloses another structure that attempts to solve the uneven distribution problem. Liebmann provides an elongate distribution channel having multiple distribution apertures. Each aperture is substantially surrounded by a cylindrical riser wall having a V-shaped metering notch. The metering notches somewhat control the flow of water through the aperture onto an evaporator pad. Although the notches somewhat control the flow, it still requires a high rate of flow in order to operate properly, and a tilted disposition will continue to cause in an uneven distribution.
U.S. Pat. No. 3,975,470 to Engel attempts to resolve the problem of unequal distribution of water when the humidifier is not perfectly level by metering the flow of water to a plurality of channels. That is, this patent discloses a distribution tray having multiple channels leading away from a centrally-disposed reservoir. A V-shaped metering notch is disposed between each channel and the reservoir, and this controls the flow of water to each channel. Although such notches are useful to control and meter the amount of water to flow into each channel, they are not particularly useful for ensuring substantially uniform water distribution over the evaporation pad when the tray is tilted. That is, like Liebmann, the flow rate of the water must be relative high in order for the tray to work properly.
Yet another attempt to resolve the problem of uneven distribution is disclosed in U.S. Pat. No. 4,125,576 to Kozinski which discloses a water distributor trough. The trough has a plurality of channels leading away from a centrally-disposed, raised target element such that when water is discharged from a supply hose, it contacts the target element and has a substantially even opportunity to run along any of the channel walls before falling into any one of the channels. However, the water dropping onto the target element must have sufficient velocity to provide enough momentum to travel along the walls before spilling into the channels.
One disadvantage of this design is the relatively small target area that the incoming water must contact to be properly distributed. When the humidifier is installed even at the slightest angle, the exact location of the incoming water is altered. Thus, by tilting the distribution tray, the even distribution of water into the channels is lost. Another disadvantage is the relatively high flow rate of water that is required to evenly distribute the water. The relatively high flow rate results in waste and causes the humidifier to be inefficient.
In each of the above examples, a high flow rate is necessary in order to solve the problem of uneven distribution. Typically, the flow rate for these humidifiers is on the order of 6 to 7 gallons of water per hour. Since only about 0.75 gallons of water are typically evaporated per hour, it is easily to understand that these humidifiers are extremely inefficient.
In view of the foregoing, it is desirable to provide a humidifier having a liquid distribution tray that substantially evenly distributes liquid from a single source to a plurality of delivery points over the evaporator pad, regardless of the flow rate of the water and even when the tray is not perfectly level. A flow rate of 3 gallons per hour or less would be considered much more efficient.
Beyond the housing, evaporator means and water distribution means, humidifiers typically include a mounted containment base which separately attaches to the air duct or furnace plenum and provides for the housing to be mounted thereon. Also typically included is some sort of water containment device or drain pan disposed below the evaporator means for collecting water run-off. A drain in the bottom of the pan provides an outlet for disposal of any excess water. The production of each of these separate parts further add to the cost of manufacturing a humidifier. Thus, it is believed desirable to reduce the number of parts and, in turn, the cost of production thereof.
In addition to these parts, a water solenoid is often disposed outside of the housing to control the flow of water to the humidifier. Typically, the solenoid is held in place by a bracket or similar means for attaching it to the housing. See, for example, the drawings in U.S. Pat. Nos. 3,975,470 and 4,158,679. Unfortunately, having the solenoid on the outside of the housing prevents the humidifier from being placed close to an object adjacent the solenoid. Thus, the need exists for a humidifier which incorporates the water solenoid to the extent that the housing can be placed adjacent an object on any side of the housing.
For those humidifiers not having fans to force air through the humidifier, conduit is often used to provide air flow between the hot air and cold air plenums. The conduit is typically attached to the humidifier using a by-pass collar. Some humidifiers are manufactured so that the humidifier can be placed on either of the hot air or cold air plenum with a by-pass collar extending toward the other plenum.
For example, if the humidifier is installed on the hot air plenum to the right of the cold air plenum, the by-pass collar will preferably extend from the left of the humidifier. On the other hand, if the humidifier is installed on the cold air plenum to the left of the hot air plenum, the humidifier can be reversed, turned upside down, or otherwise reconfigured such that the by-pass collar will extend from the right of the humidifier. Thus, while interchangeable and/or reversible by-pass collars exists, there has not heretofore been a humidifier which will accept an additional by-pass collar. The use of two by-pass collars is believed desirable inasmuch as the performance of the humidifier can be enhanced significant when additional air flows through it. Thus, the need exists for the capability of adding two by-pass collars to the humidifier for performance enhancement.